Fire damper blade latch

ABSTRACT

A pivotally mounted latch for a fire damper blade which is mounted to swing on a horizontal axis between an open position and a closed position. The damper is adapted to be mounted across either a horizontal or a vertical duct. The blade is normally held open by a fire responsive release and is weighted to swing by gravity to closed position across the duct when released. The latch is mounted on the outer side of the blade on a pivot axis parallel to that of the blade and extends through a slot in the blade. The latch has a plate with a generally arcuate edge which is eccentric to its pivot and which strikes a catch as the blade closes. The eccentricity of the latch plate weighs the plate to swing it into locked position behind the catch when the damper blade reaches closed position. The latch operates effectively whether the fire damper is mounted in a horizontal or a vertical position.

United States Patent Alley 1451 Mar. 21, 1972 54 FIRE DAMPER BLADE LATCH1,094,961 4 1914 [72] Inventor: Raymond L. Alley, Toledo, Ohio [73]Assignee: American Warming & Ventilating, Inc., 2 1941 Toledo, OhioPrimary Examiner-Dennis L. Taylor [22] Flledz Aug. 31, 1970 Au0mey Owen& Owen [21] Appl. No.. 61,268 [57] CT Appuuuon Data A pivotally mountedlatch for a tire damper blade which is [63] Continuation-impart of Ser.No. 30,225, Apr. 20, mounted to swing on a horizontal axis betwwl an p P1970 abandone tion and a closed position. The damper is adapted to bemounted across either a horizontal or a vertical duct. The 52 us. 01..49/7, 292/136 blade is normally held p y a fire responsive release andis s 1 1 ..Eo5r 15/20 Weighted to Swing y r y to closed position acrossthe duct [58] Field of Search ..49/7, 8, 503, 394; 292/136, W119" Thelatch is mount on the side of the 292/238 104 blade on a pivot axisparallel to that of the blade and extends through a slot in the blade.The latch has a plate with a [56] Retercnces Cited generally arcuateedge which is eccentric to its pivot and which strikes a catch as theblade closes. The eccentricity of UNITED STATES PATENTS the latch plateweighs the plate to swing it into locked position behind the catch whenthe damper blade reaches closed posi- 2'270'073 942 Men'y "49/7 X tion.The latch operates effectively whether the tire damper is 130013964/1931 Mohun '49/394 X mounted in a horizontal or a vertical position.

122,615 1/1872 Knight 1 ..49/7 X 168,525 10/1975 Peterman ..292/136 3Claims, 7 Drawing Figures PAIENIEB MAR 21 I972 SHEET 1 [IF 2 TIE-Z-INVENTOR: HAYMUNU L. ALLEY BY r j @K A TTZYS'.

PATENTEDMARZI I972 SHEET 2 [IF 2 r /d a INVENTOR.

RAYM 0ND L ALLE Y ATTYS' 40a lggmmsccasssesst TTE'E' FIRE DAMPER BLADELATCH This application is a continuation-in-part of my copendingapplication Ser. No. 30,225, filed Apr. 20, 1970 now abandoned.

BACKGROUND OF THE INVENTION This invention relates to a tire damperhaving a pivoted blade latch.

l-Ieretofore, if latches were employed with fire damper blades, theyutilized springs, either in the form of spring catches orspring-actuated latches. Such devices required a substantial amount offorce to operate properly. In the event of a fire, the resiliency of thespring also could be destroyed by the heat, causing the latch to fail.

The fire damper in accordance with the instant invention employs apivoted, gravity-operated latch requiring no springs whatsoever. Thelatch thereby requires little force to operate and is reliable inoperation. Further, the fire damper employing this latch operateseffectively in either a horizontal or vertical installation.

It is, therefore, a principal object of the invention to provide a firedamper with an improved latch having the advantages outlined above.

Numerous other objects and advantages of the invention will be apparentfrom the following detailed description of a preferred embodimentthereof, reference being made to the accompanying drawings, in which:

FIG. I is a fragmentary view in perspective of two fire damperscomprising latches embodying the invention, and located side by side ina horizontal duct, one damper blade being shown in open position and theother being shown in closed position;

FIG. 2 is a vertical sectional view taken along the line 2-2 of FIG. 1;

FIG. 3 is a view similar to FIG. 2 but taken along the line 3-3 of FIG.1;

FIG. 4 is a fragmentary, enlarged sectional view of a latch and catch ofthe fire damper, in a partially closed position;

FIG. 5 is a view similar to FIG. 1 but showing two fire damperscomprising latches embodying the invention and located side by side in avertical duct;

FIG. 6 is a vertical sectional view taken along the line 6-6 of FIG. 5;and

FIG. 7 is a view similar to FIG. 6 but taken along the line 67 of FIG.5.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring particularly to FIG.1, two substantially identical fire dampers generally indicated by thereference number 10 are located in side-by-side relationship, in thisinstance, in a horizontal duct 12. The fire dampers 10 can be made inseveral standard sizes and employed singularly, side by side, stacked,or both, to extend completely across a duct or other opening which is tobe blocked in the event of fire. The fire dampers are normally held inan open position as shown by the left hand damper in FIG. 1, in whichposition they provide substantially no resistance to air passingthereby. In the event of fire or heated gases from a fire flowingthrough the duct, the dampers will close and assume the positionillustrated by the right hand damper in FIG. 1, in which instance theflow through the duct or opening is substantially stopped. Each of thetire dampers 10 perfectly is a unitin itself and is installed in theduct or opening as a complete assembly. When two or more dampers areused as an assembly, one can be affixed to the other by suitablefasteners or by welding.

Each of the dampers 10 includes an upper or first frame member 14, alower or second frame member 16, and two side frame members 18 and 20.As shown, these members are of channel-shaped configuration and arewelded together to produce an integral frame. The first frame member 14has a stop strip 22 extending longitudinally and suitably affixed to acentral portion thereof. The second frame member has a catch strip 24also extending longitudinally and suitably affixed centrally thereof.The stop 22 and the catch 24 can function effectively without extendingcompletely across the damper, but by so extending, they also serve asseals at opposite edges of the damper frame and thereby moreefi'ectively prevent passage of gases when the damper is closed.

A single damper blade 26 is of a size to close the opening formed by therespective frame members 14-20 of each of the dampers. The blade 26 hasaxles 28 and 30 extending outwardly from opposite sides thereof andreceived respectively in openings 32 and 34 in the side frame members 18and 20. The axles 28 and 30 are positioned above the center of the blade26 and the holes 32 and 34 are similarly located closer to the upperframe member 14 than the lower frame member 16 in order to weight theblade 26 to swing closed when released.

In this instance, the blade 26 is held in the open position by a linkageconnected to the edge of the blade 26 closer to the upper frame member14. An ear 36 is suitably affixed to the upper edge portion of the blade26 and has a hook 38 which connects the ear 36 to a fusible link 40. Thefusible link 40 is connected by an additional hook 42, a chain 44, and alower hook 46 to a mounting eye 48 suitably fastened to or through thelower wall of the duct 12. The fusible link 40 fuses when a certaintemperature is reached as is known in the art, thereby to release theblade 26 to swing downwardly by gravity to closed position.

When the blade 26 is held in the open position by the fusible link 40and associated components, the larger portion of the blade 26 on theopposite side of the axles 28 and 30 bears against a stop 50, as shownin FIG. 1, to prevent the possibility of unwanted movement or waveringof the blade as fluids through the duct 12.

When the link 40 fuses, the unbalanced blade 26 swings shut so that theupper edge thereof contacts the stop 22 and the other edge contacts thecatch 24. Particularly with a high volume of heated gases, it isdesirable that the damper blade be positively held shut when closed.I-Ieretofore, this has been accomplished by various spring catches orspring-actuated latches. These, however, have required a considerableamount of force to be moved properly and also are subject to failure dueto heat from the fire.

The latching arrangement embodying the invention overcomes thesedisadvantages and is also reliable and effective in operation. A latchembodying the invention is indicated at 52 and comprises a latch plate54 pivotally carried on a bracket 56 which is affixed, as by rivets, tothe outer side of the edge portion of the blade 26 which lies adjacentthe catch 24 when the blade is closed. The latch plate 54 includes ashank portion 58 which is pivoted by a suitable pin or rivet 60 to thebracket 56 with the shank integrally connected to a heavy cam portion62. The cam portion 62 has a generally arcuate cam edge 64 which strikesthe catch 24 as the blade 26 closes to swing the latch plate 54upwardly, in a clockwise direction as shown in broken lines. The latchplate 54 thereby is elevated above the catch 24, and, when the edge ofthe blade 26 strikes the catch 24, the latch plate 54 snaps downwardly,i.e., radially relative to the axles 28 and 30. A latching edge 66 ofthe cam portion 62 swings downwardly behind and engages the catch 24.The edge 66 preferably diverges outwardly from the plane of the blade 26somewhat to assure that the latch will engage the catch and will notbounce away from it. As the latch plate 54 snaps downwardly the upperedge of the catch 24 is wedged between the latching edge 66 and theinner side of the blade 26. This assures a maximum sealing effectbetween the blade 26 and the fire damper frame.

The cam portion 62 of the latch plate 54 is located on the inner side ofthe damper blade 26 and the shank portion 58 on the opposite side of theblade, extending through a slot 68 which is generally perpendicular tothe axis of the axles 28 and 30. The lower edge of the slot 68 is solocated as to prevent the latch plate 54 from being swung radiallyoutwardly too far to engage the catch 24 as the blade swings toward theclosed position, as shown in FIG. 4. When the latch plate 54 moves overthe catch 24 and snaps downwardly, the catch 24 is wedged between theedge 66 and the blade 26 before the latch plate 54 can move to itslowest position against the lower edge of the slot 68. The upper edge ofthe slot 68 limits the upward movement of the latch plate 54 to preventthe possibility of the latch plate bouncing excessively when carnmedupwardly by the catch 24 during closing movement of the blade 26.

While the shape of the cam portion 62 is shown as generally arcuate, itcan vary substantially, it being only important that the edge 64 iseffective to force the latch plate 54 in the direction opposite to thedirection it is urged by gravity. Also, the cam portion 62 must beeccentric to the rivet 60 and of sufficient weight to urge the latchplate 54 toward the latching position, in a counterclockwise direction,as shown in the drawing.

While the latch has been disclosed specifically in connection with asingle-blade fire damper, it can be used with equal efficacy with firedampers having more than one mechanically connected blade.

FIGS. 5, 6 and 7 show a pair of dampers 10a positioned across a verticalduct 12a, the dampers 10a being identical in every respect with thedampers 10 illustrated in FIGS. l -4 and all of their structure anddetails corresponding to the structure and details of the dampers 10 asdescribed above.

In the arrangement illustrated in FIGS. 5, 6 and 7, however, damperblades 26a extend generally vertically when in open position and liehorizontally when in closed position. It will also be observed in FIG.that the damper blade 26a at the left side of the drawing is notprecisely vertical but is inclined fonvardly slightly relative to thevertical so as to be weighted to swing downwardly into the closedposition illustrated at the right side of FIG. 5 when its fusible link40a is released in response to fire or heat.

As can best be seen by comparing FIGS. 1 and 5 the damper blade 26a isidentical with the damper blade 26 of FIGS. l-4, inclusive and, in openposition, is positioned the same relative to its frame. The blade 26ahas a latch 52a identical in every respect with the latch 52 shown inFIGS. l-4. When its fusible link 40a releases the blade 26a, gravityswings the blade downwardly to the right (in a clockwise direction) and,as in the case when the damper is in the vertical position illustratedin FIGS. l-4, inclusive, engagement of the generally arcuate cam edge64a with the edge of its associated catch 24a causes the latch 52a to besnapped sharply in a clockwise direction around its pivot 60a a degreeof arcuate movement limited by the inner edge of its slot 68a. As theouter edge of the damper blade 26a strikes the catch 240, the eccentricweighting of the latch 52a and its inertia cause it to fly radiallyoutwardly relative to the damper blade axles 28a and 30a snapping itsharply outwardly beneath the catch 24a to wedge the catch 240 againstthe inner (in this case lower) side of the tion as shown in FIGS. l-4,inclusive,

edge portion of the damper blade 260.

Details of construction, sizes, shapes, function and operation of thedamper having a catch embodying the invention are identical whether thedamper is arranged in vertical posior in horizontal position as shown inFIGS. 5-7, inclusive. In either orientation, the eccentric weighteddesign of the latch 52 or 520 and its positioning at the edge of theblade 26 or 260 results in the latch 52 or 52a functioningautomatically, precisely and definitely with no likelihood either thatit will bounce open and remain unlatched when the damper blade 26 or 26areaches closed position or that it will fail to remain in latchedposition after once having been closed.

I claim:

1. An automatic fire damper comprising a frame lying generally in aplane and defining an opening for the flow of air therethrough in adirection generally normal to the plane of said frame, a blade fittingsuch opening for closing the same upon the occurrence of a fire,cooperating axially aligned pivot means on said frame and said bladeproviding for angular movement of said blade between a closed positionacross said 0 ening and an open position, said blade being biased towarclosed position when in such open position, heat fusible means forholding said blade in open position, a catch on said frame protrudingtherefrom into such opening generally parallel to the plane of saidframe and a latch pivotally mounted on said blade at a position toengage said catch when said blade moves into closed position, said latchhaving an integral weighted portion offset horizontally relative to itspivot point for swinging said latch into engagement over said catch uponmovement of said blade to closed position both when said frame lies in ahorizontal plane and when said frame lies in a vertical plane.

2. A fire damper according to claim 1 in which the catch on the frame isa flat bar extending parallel to the pivot line of the pivot means andthe latch is pivoted on an axis parallel to such pivot line.

3. A fire damper according to claim 2 in which the latch has a camportion engageable with said catch as said blade moves to closedposition and said cam portion is weighted for causing said latch to fallover said catch when said blade reaches closed position.

1. An automatic fire damper comprising a frame lying generally in aplane and defining an opening for the flow of air therethrough in adirection generally normal to the plane of said frame, a blade fittingsuch opening for closing the same upon the occurrence of a fire,cooperating axially aligned pivot means on said frame and said bladeproviding for angular movement of said blade between a closed positionacross said opening and an open position, said blade being biased towardclosed position when in such open position, heat fusible means forholding said blade in open position, a catch on said frame protrudingtherefrom into such opening generally parallel to the plane of saidframe and a latch pivotally mounted on said blade at a position toengage said catch when said blade moves into closed position, said latchhaving an integral weighted portion offset horizontally relative to itspivot point for swinging said latch into engagement over said catch uponmovement of said blade to closed position both when said frame lies in ahorizontal plane and when said frame lies in a vertical plane.
 2. A firedamper according to claim 1 in which the catch on the frame is a flatbar extending parallel to the pivot line of the pivot means and thelatch is pivoted on an axis parallel to such pivot line.
 3. A firedamper according to claim 2 in which the latch has a cam portionengageable with said catch as said blade moves to closed position andsaid cam portion is weighted for causing said latch to fall over saidcatch when said blade reaches closed position.